The U.S. Steel Plant Duluth Works Site, a former steel mill and coking operation, is on both the federal National Priorities List (NPL) and the State of Minnesota Permanent List of Priorities (PLP). The site is approximately 600 acres (500 land and 100 river sediment). It is located 4 miles south-west of the Duluth central business district and adjacent to the neighborhood of Morgan Park.
The U.S. Steel Site has 18 Operable Units (OU) within the 1989 Record of Decision (ROD) for remedial action, as well several other components that were not identified as OUs. In 2016 the Minnesota Pollution Control Agency (MPCA) requested that U. S. Environmental Protection Agency (EPA) take the lead project management role for the contaminated aquatic sediment Operable Units (OUs-I, L, M, N, P, Q, and R), and associated areas without a separate OU designation, known as "I/J" and "unnamed pond" at the Site. The EPA and the United States Steel Corporation (USS) have entered into a partnership to cleanup impacted sediment within the Spirit Lake area of the St. Louis River. This work began in 2020 and is being conducted under a Great Lakes Legacy Act project agreement between EPA and USS. The purpose of the project is to address chemical constituents of concern, primarily polycyclic aromatic hydrocarbons (PAH) and metals including copper, lead, and zinc. The cleanup includes dredging, capping, and long term monitoring of impacted sediments.
EPA project page: U.S. Steel/ Spirit Lake Sediment Remediation Project